I see there is a valid argument to be made for a title being optimized to a certain platform, in that developers can get the most out of a game from a performance angle.  Besides this, why should anyone care that a game is an exclusive to a certain platform?  If a game appears on your platform of choice, but also others, why should it matter?  Why would the likes of MGS4 jumping to the XBox 360, or Gears on the PS3, really upset people, for example?

Ammo for LIST WARZ~!, I guess.

Because I love Microsoft and Xbox and I want them to win.

The only other reason I can think of would be console identity.  If every game came out on every console why would there be a need for different consoles?   But the main point is exactly what you said though,  Optimization for that console,  they always seem to be better games when this is the case.  

avoid dispersal of resources.

If there was only one platform, all the resources would be put thowards perfecting the game on that platform

Because each console maker has a certain belief about how to further the industry and have their own views on how to do it.  As a gamer, you may agree with one more than any other.  Hence, you may want them to be the most successful.  That's where exclusives come in.  For me, that's Sony.

I wouldn't wanna see Mario or Zelda franchise on the PS3 or the 360. Exclusive games makes each system unique by what they offer that other systems don't.

I don't believe a game is better because it's exclusive. If it's good then I'll play it. The problem here is that unlike many, not everyone wants to buy multiple consoles, I have bought a 360 because I wanted a game console that plays Halo but if Halo was multi maybe I would've bought the cheaper one that provided the best experience.

There's something that is sad about video games and it's the fact that unless it's emulated, when one wants to play an older game he has to buy a specific console where as movies you could just buy the medium player not the company behind it.

The other sad thing is that gamers that pledge allegiance to one specific company don't realise that most companies want to make a profit and to do so they have to make their work available to all platforms. Because of this a lot of them believe that a game that releases on a "rival" platform must be inferior to the games that don't.

I used to be like this but then I was 10-12.

That depends. There are many exclusives on each console that wouldn't have been what they are or at all if it wasn't for exclusivity.

This. Exclusivity making games better sounds, in most cases, to me to be a desperate fanboy myth.